Question regarding unlocking iPhone for T-Mobile

I have a first-gen iPhone and at&t is just too expensive. I canceled my account with them and I am planning on getting T-Mobile tomorrow. I've been reading the threads and I'm pretty sure I can run QuickPwn and unlock/jailbreak the phone myself, but I have a question regarding the T-Mobile sim card:

Do I need to have the T-Mobile sim card in the iPhone BEFORE I run QuickPwn? Or, do I need to run QuickPwn and then insert the sim?

I haven't found any threads regarding this, and I wanted to make sure because I have run QuickPwn once before and put a friend's T-Mobile sim in my iPhone afterwards and it didn't work.

But if it were me, I'd use pwnage tool to create a custom ipsw and to unlock the baseband, then use iTunes to load this onto the iPhone without a SIM in it. Then put the Tmobile SIM in after it's been unlocked.

I am pretty sure this is the method I used when I gave my first gen to my girlfriend for her use on Tmobile.

But if it were me, I'd use pwnage tool to create a custom ipsw and to unlock the baseband, then use iTunes to load this onto the iPhone without a SIM in it. Then put the Tmobile SIM in after it's been unlocked.

I am pretty sure this is the method I used when I gave my first gen to my girlfriend for her use on Tmobile.

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